Marine Seismic Receiver Channels for Extended Dynamic Range
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Solution Overview
Problem
Traditional marine seismic receivers are prone to saturation and noise issues when recording short, zero, or negative offset seismic reflections due to the close proximity of the seismic source, leading to loss of direct wave information and reflection energy.
Innovation Solution
Implementing seismic data acquisition channels with varying saturation limits and dynamic ranges by deploying channels with higher saturation limits and noise floors in proximity to the source, and conventional channels further away, along with techniques to combine subchannels with different sensor sensitivities to create a hybrid waveform.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional seismic receivers are used at short offsets, then recording capability is provided, but saturation and noise issues occur leading to loss of direct wave information and reflection energy
Solution Approach 1:
The streamer is divided into multiple sections with different receiver types. Near-source sections contain high saturation limit receivers, while far-source sections contain conventional receivers. This segmentation allows each receiver type to operate in its optimal performance range, resolving the contradiction between recording capability and data quality at different offset distances.
Solution Approach 2:
Different receiver characteristics are assigned to different spatial locations along the streamer. Receivers near the source have higher saturation limits to handle strong direct waves, while receivers farther away use conventional specifications optimized for weaker reflection energy. This local differentiation resolves the contradiction by matching receiver capabilities to local signal characteristics.
2Loss of information
If high saturation limit receivers are deployed throughout the streamer, then direct wave information is preserved, but reflection energy recording capability deteriorates due to increased noise floor
Solution Approach 1:
The streamer is segmented into near-source and far-source sections. High saturation limit receivers are deployed only in near-source sections where direct wave information is present, while conventional receivers are used in far-source sections where only reflection energy exists. This segmentation ensures direct wave information is preserved where needed without degrading reflection energy recording capability elsewhere.
Solution Approach 2:
Receiver specifications are optimized for local signal conditions. Near-source receivers have high saturation limits to capture direct waves, while far-source receivers have lower noise floors to capture weak reflections. This local optimization resolves the contradiction by applying different receiver qualities to different spatial zones.
3Ease of manufacture
If conventional streamer configuration is used, then equipment cost is reduced, but capability to record both direct and reflection energy is limited
Solution Approach 1:
The streamer is configured with segmented receiver sections rather than uniform receivers throughout. This allows the system to achieve extended functionality by using different receiver types only where needed, rather than upgrading all receivers. The near-source section gets high saturation limit receivers while the far-source section uses conventional receivers, providing versatility at minimal additional cost.
Solution Approach 2:
Enhanced receiver capabilities are applied locally only where required (near-source section) rather than uniformly throughout the entire streamer. This localized enhancement provides the versatility to record both direct and reflection energy while minimizing the cost increase, as only a portion of the receivers need the enhanced specifications.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Enables accurate recording of both direct and reflection seismic energy across a wide range of amplitudes, preserving valuable data and reducing equipment costs by optimizing channel deployment.
Implementation Method 1
one or more marine seismic sources are activated at intervals to produce acoustic energy that propagates through a body of water into a subsurface earth volume
Implementation Method 2
The acoustic energy produced by the source or sources penetrates layers of sediment and rock in the subsurface. As it does so, the energy encounters interfaces between materials having different physical characteristics, including different acoustic impedances. At each such interface, a portion of the acoustic energy is reflected upward
Implementation Method 3
The reflected energy is detected by sensors--also referred to as receivers--that are disposed at intervals along the lengths of towed streamers
Implementation Method 4
The seismic reflections that are detected by the sensors are recorded for later use in a process known as seismic imaging
Data Source
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AI summary
A marine seismic data acquisition apparatus is provided, comprising: a sensor, a first data acquisition subchannel configured to exhibit a first gain and comprising a first subchannel input, and a second data acquisition subchannel configured to exhibit a second gain lower than the first gain. The sensor output and first and second input protection circuits are configured such that neither the first input protection circuit nor the second input protection circuit will activate when seismic energy reaching the sensor has a peak amplitude less than a first threshold level. The internal input protection circuit is configured to activate when seismic energy reaching the sensor has a peak amplitude greater than a second threshold level, wherein the second threshold level is lower than the first threshold level.